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  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      height: 100px;
      /* width: 20px; */
      border: solid 1px #1616;
    }

    span {
      font-size: 20px;
      line-height: 100px;
    }
  </style>
</head>

<body>
  <div>
    <span>行距 = line-height - font-size，缺点是要有足够宽度容纳同一行</span>
  </div>
</body>

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